Effect of atmosphere on the electrical properties of TiO2-SnO2 varistor systems

• Published in: Journal of materials science. Materials in electronics Vol. 15; no. 10; pp. 665 - 669
• Main Authors: SOUSA, V. C, CASSIA-SANTOS, M. R, BARRADO, C. M, BOMIO, M. R. D, LEITE, E. R, VARELA, J. A, LONGO, E
• Format: Journal Article
• Language: English
• Published: Norwell, MA Springer 01-10-2004; Springer Nature B.V
• Subjects: Applied sciences; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Grain size; Materials; Grain size; Low voltage; Heat treatment; Electric field; Electric breakdown; Adsorption; Polycrystal; Varistance; Electrical characteristic; Electroceramics; Grain boundary
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1023/B:JMSE.0000038921.07744.9d

Results are presented that show that the addition of different dopants, and thermal treatments in oxidising and inert atmosphere, influences the densification, the mean grain size and the electrical properties of TiO2-based varistor ceramics. Dopants like Ta2O5, Nb2O5, and Cr2O3 have a special role in the barrier formation at the grain boundary in the TiO2 varistors, increasing the nonlinear coefficient and decreasing the breakdown electric field. The influence of Cr'(Ti) is to increase the O' and O'2 adsorption at the grain boundary interface and to promote a decrease in the conductivity by donating electrons to O2 adsorbed at the grain boundary. TiO2 and (Sn,Ti)O2-based studies of polycrystalline ceramics, which show a non-linear I-V electrical response typical of low voltage varistor systems, are also presented. All these systems are potentially promising for varistor applications. 17 refs.